1. Field of Invention
This invention relates to malfunction diagnosis of banding defects in document processing systems based on defect feature analysis and machine data analysis.
2. Description of Related Art
In document processing systems, it is well known that customer satisfaction can be improved and maintenance costs reduced if problems with copiers and printers can be fixed before they become serious enough to warrant a service call by the customer. Systems exist that enable printers and copiers to call for service automatically, when sensors detect certain operating parameters outside of permissible ranges. Generally, these systems take effect after a threshold has been reached where the degradation in image quality is directly observable by the user. Given the large number of operating parameters that need to be tracked during operation, a specific defect at a certain level may or may not be a significant problem. The overall affect of a specific defect depends on the cumulative values of the other parameters in the system. Systems do exist that attempt to diagnose failures in document processing systems based on image quality analysis of the print. Such a system for the diagnosis of copier performance over telephone lines is described in U.S. Pat. No. 5,365,310, incorporated herein by reference in its entirety.
A system and method for automatically diagnosing image quality defects is described in U.S. patent application Ser. No. 464,596, filed on Dec. 16, 1999, now U.S. Pat. No. 6,665,425 and commonly owned with the subject invention. The disclosure of this application is incorporated herein in its entirety. In this system, image quality problems occurring in a document processing system are identified by applying image processing and pattern recognition techniques to analyze specific test patterns. The results are analyzed in conjunction with known generic or experienced unit specific machine data in a diagnostic expert system to determine the cause of the problem. Further systems are provided to determine and execute a recommended service procedure, such as a user guided repair; scheduled maintenance service, parts replacement, and the like.
One of the most frequently encountered image defects is the banding defect which is symptomatic of a wide variety of malfunctions in the performance of a document processor. These defects manifest themselves as one or more lines, streaks, or bands extending across the document copy parallel to the short edge or the long edge, and may be periodic or non-periodic. They are caused by worn or damaged parts, foreign matter, electrical malfunctions, misalignment and other sources, within the print engine and the associated feed mechanisms and controls.
It is a purpose of the methods and systems described in this application to provide a means by which banding defects may be identified, analyzed, and quantified. It is a further purpose to diagnose a probable source of the defect and propose to the user an appropriate repair or correction.